Acetyl-CoA carboxylases (ACC) are a family of enzymes found in most species and are associated with fatty acid synthesis and metabolism through catalyzing the production of malonyl-CoA from acetyl-CoA. In mammals, two isoforms of the ACC enzyme have been identified. ACC1, which is expressed at high levels in lipogenic tissues, such as fat and the liver, controls the first committed step in the biosynthesis of long-chain fatty acids. If acetyl-CoA is not carboxylated to form malonyl-CoA, it is metabolized through the Krebs cycle. ACC2, a minor component of hepatic ACC but the predominant isoform in heart and skeletal muscle, catalyzes the production of malonyl-CoA at the cytosolic surface of mitochondria, and regulates how much fatty acid is utilized in β-oxidation by inhibiting carnitine palm itoyl transferase. Thus, by increasing fatty acid utilization and by preventing increases in de novo fatty acid synthesis, chronic administration of an ACC inhibitor (ACC-I) may also deplete liver and adipose tissue triglyceride (TG) stores in obese subjects consuming a high or low-fat diet, leading to selective loss of body fat.
Studies conducted by Abu-Etheiga, et al., suggest that ACC2 plays an essential role in controlling fatty acid oxidation and, as such it would provide a target in therapy against obesity and obesity-related diseases, such as type-2 diabetes. See, Abu-Etheiga, L., et al., “Acetyl-CoA carboxylase 2 mutant mice are protected against obesity and diabetes induced by high-fat/high-carbohydrate diets” PNAS, 100(18) 10207-10212 (2003). See also, Choi, C. S., et al., “Continuous fat oxidation in acetyl-CoA carboxylase 2 knockout mice increases total energy expenditure, reduces fat mass, and improves insulin sensitivity” PNAS, 104(42) 16480-16485 (2007).
It is becoming increasingly clear that hepatic lipid accumulation causes hepatic insulin resistance and contributes to the pathogenesis of type 2 diabetes. Salvage, et al., demonstrated that ACC1 and ACC2 are both involved in regulating fat oxidation in hepatocytes while ACC1, the dominant isoform in rat liver, is the sole regulator of fatty acid synthesis. Furthermore, in their model, combined reduction of both isoforms is required to significantly lower hepatic malonyl-CoA levels, increase fat oxidation in the fed state, reduce lipid accumulation, and improve insulin action in vivo. Thus, showing that hepatic ACC1 and ACC2 inhibitors may be useful in the treatment of nonalcoholic fatty liver disease (NAFLD) and hepatic insulin resistance. See, Savage, D. B., et al., “Reversal of diet-induced hepatic steatosis and hepatic insulin resistance by antisense oligonucleotide inhibitors of acetyl-CoA carboxylases 1 and 2” J Clin Invest doi: 10.1172/JCI27300. See also, Oh, W., et al., “Glucose and fat metabolism in adipose tissue of acetyl-CoA carboxylase 2 knockout mice” PNAS, 102(5) 1384-1389 (2005).
Consequently, there is a need for medicaments containing ACC1 and/or ACC2 inhibitors to treat obesity and obesity-related diseases (such as, NAFLD and type-2 diabetes) by inhibiting fatty acid synthesis and by increasing fatty acid oxidation.